LNK302/304-306
®
LinkSwitch-TN Family
Lowest Component Count, Energy-Efficient
Off-Line Switcher IC
Product Highlights
Cost Effective Linear/Cap Dropper Replacement
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Lowest cost and component count buck converter solution
Fully integrated auto-restart for short-circuit and open
loop fault protection – saves external component costs
LNK302 uses a simplified controller without auto-restart
for very low system cost
66 kHz operation with accurate current limit – allows low cost
off-the-shelf 1 mH inductor for up to 120 mA output current
Tight tolerances and negligible temperature variation
High breakdown voltage of 700 V provides excellent
input surge withstand
FB
BP
S
D
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+
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Wide Range
HV DC Input
DC
LinkSwitch-TN
Output
PI-3492-111903
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Figure 1. Typical Buck Converter Application (See Application
Examples Section for Other Circuit Configurations).
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Frequency jittering dramatically reduces EMI (~10 dB)
– minimizes EMI filter cost
High thermal shutdown temperature (+135 °C minimum)
OUTPUT CURRENT TABLE1
230 VAC ±15%
MDCM2 CCM3 MDCM2 CCM3
LNK302P/G/D 63 mA 80 mA 63 mA 80 mA
85-265 VAC
PRODUCT4
Much Higher Performance over Discrete Buck and
Passive Solutions
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Supports buck, buck-boost and flyback topologies
System level thermal overload, output short-circuit and
open control loop protection
LNK304P/G/D 120 mA 170 mA 120 mA 170 mA
LNK305P/G/D 175 mA 280 mA 175 mA 280 mA
LNK306P/G/D 225 mA 360 mA 225 mA 360 mA
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Excellent line and load regulation even with typical
configuration
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High bandwidth provides fast turn-on with no overshoot
Current limit operation rejects line ripple
Universal input voltage range (85 VAC to 265 VAC)
Built-in current limit and hysteretic thermal protection
Higher efficiency than passive solutions
Higher power factor than capacitor-fed solutions
Entirely manufacturable in SMD
Table 1. Output Current Table.
Notes:
1. Typical output current in a non-isolated buck converter. Output power
capability depends on respective output voltage. See KeyApplications
Considerations Section for complete description of assumptions,
including fully discontinuous conduction mode (DCM) operation.
2. Mostly discontinuous conduction mode.
3. Continuous conduction mode.
4. Packages: P: DIP-8B, G: SMD-8B, D: SO-8C.
EcoSmart®– Extremely Energy Efficient
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Consumes typically only 50/80 mW in self-powered buck
topology at 115/230 VAC input with no load (opto feedback)
Consumes typically only 7/12 mW in flyback topology
with external bias at 115/230 VAC input with no load
Meets California Energy Commission (CEC), Energy
Star, and EU requirements
LinkSwitch-TN devices integrate a 700 V power MOSFET,
oscillator,simpleOn/Offcontrolscheme,ahighvoltageswitched
currentsource, frequencyjittering, cycle-by-cyclecurrentlimit
and thermal shutdown circuitry onto a monolithic IC. The start-
up and operating power are derived directly from the voltage
on the DRAIN pin, eliminating the need for a bias supply and
associated circuitry in buck or flyback converters. The fully
integrated auto-restart circuit in the LNK304-306 safely limits
output power during fault conditions such as short-circuit or
open loop, reducing component count and system-level load
protection cost. A local supply provided by the IC allows use
of a non-safety graded optocoupler acting as a level shifter to
further enhance line and load regulation performance in buck
and buck-boost converters, if required.
Applications
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Appliances and timers
LED drivers and industrial controls
Description
LinkSwitch-TN is specifically designed to replace all linear and
capacitor-fed (cap dropper) non-isolated power supplies in the
under 360 mA output current range at equal system cost while
offering much higher performance and energy efficiency.
November 2008